1. Field of the Invention
This invention relates to a labelling station for objects, in particular bottles, with several stations located behind one another along a track, comprising an adhesive or glue application apparatus, a label supply station and a label transfer station. The invention has at least one extracting element which can rotate on a rotating support and be moved past the stations during each rotation of the support.
The extracting element has an outwardly-curved receptacle surface to receive the label as the extracting element moves or rolls past the stations. The drive mechanism for each extracting element is a cam drive, which comprises common, stationary double cam discs for all the extracting elements with the cams located on one side of the drive mechanism and in two different planes, one plane being above the other and at some distance from the other.
Two sets of followers are mounted on the drive shaft or on a bearing shaft which is coupled with the drive shaft by means of a support element. The positive, directed movement of each extracting element over its entire revolution as the support rotates is protected by means of a form-fit with the two cam surfaces.
2. Background Information
The prior art includes various cam-controlled drive mechanisms to turn the extracting elements in labelling machines at the various stations in the same direction with different angular velocities over the entire orbit.
In a first drive system of the prior art (German Patent No. 24 36 003 P2), the extracting elements are always driven by a pair of lever arms, which are guided with a follower in a closed grooved cam. The partly-overlapping grooved cams are in different planes, to allow for an unobstructed path while guided by the lever arms. Each follower is clearly guided or directed as positioned on the two flanks of the corresponding grooved cam. The grooved cams are configured so that the one follower is under torque when the other follower is in an idle position. However, such a drive mechanism has not been used in actual practice.
Further, it has not been possible to utilize in actual practice another drive mechanism for a labelling machine of the type described above (German Patent No. 27 09 521 A1). In the description of the drive mechanism in this patent, there are two cam discs with outside cams located in two planes, one plane above the other. There is a set of two followers, each of which correspond to the two cam discs in two different planes. The two pairs of followers are offset on the upper and lower side of a disc by 90 degrees in relation to one another. The disc is supported by a bearing shaft which extends to the plane between the cam discs. It cannot be determined from the prior art whether precautions have been taken in the design of the drive mechanism to provide for a collisionfree passage area, for example, an open space which the bearing shaft does not enter. According to the present invention, the open space or collision-free area is preferably located outside the radial areas of the cam disc adjacent to the bearing shaft.
According to U.S. Pat. No. 42 98 422, a labelling machine of the type described above, but with another drive mechanism, has been used in actual practice . In this labelling machine, the cam drive mechanism is designed as a lantern gear transmission, with two sets of lantern gear teeth located on the inside of the double cam disc which disc is in the shape of a ring-like body. The support element, which supports one set of the followers designed as lantern wheels on its two sides, is located between the two lantern gears on the end of the drive shaft of the extracting element with the drive shaft extending to the end point. The points of the teeth of this lantern gear are cut off to provide for a collision-free passage of the drive shaft along the lantern gear on the shaft side. With this type of drive mechanism, of course, a non-uniform rotation of the extracting elements can be achieved, but the cost and complexity of the lantern gear transmission is quite high. A further disadvantage is that the radial diameter of the lantern gears cannot be very compact on account of the minimum width of the individual teeth required.